Tuesday, 15 November 2016

Testing U3S now on 30m

Another LPF finished and installed on my Ultimate 3S beacon. This one is in the position 5 slot, so maintaining the increasing frequency order (40m in slot 0 on the main board, 30m in 5, 20m in 4, and so far 10m in slot 1)

So far its been received nicely across Western and Northern Europe, and into the central region, but also across the pond into Florida. Not bad for a touch under 23dBm into the antenna system, and that not perfectly matched.

The only gripe I have is that there is no clear space on the componant side of the LPFs to mark which band they are tuned for. I have written the band on the underside of the PCBs, but thats not visible when they are plugged in. I might mention this to Hans on the group, but I dont know how he could adjust the design to provide a write space, as the boards are very compact. Perhaps a few mm extra board on one end and a white silkscreen?

Saturday, 12 November 2016

Ultimate 3S Relay kit

The relay board kit and extra LPFs for my U3S beacon arrived yesterday, so I found some time to work on them today.

As with all Hans' kits, its very compact but goes together very easily, excellent quality. I did find the nylon pillars were a bit awkward to fit due to being so close to other components, something that would not be a problem if the stand-off for the display was screwed into it, rather than the other way around. I removed my pins connecting the RF out, then realised I could leave them, and tried to put them back but couldnt clean the holes out properly and ended up making a mess of it! So they were left out permanently. Not to worry though, im unlikely to revert to single band operation.

The above shows the relay board fitted onto the U3S. This is revision 5 of the board, which includes a novel modification to increase the harmonic suppression performance, but it does require the highest frequency LPF (in my case 10m) to be left permanently installed in position 1. Position 0, that is, the LPF location on-board the U3S, I have left my other original filter for 40m installed. This leaves me four positions for my four new filters - 30m, 20m, 17m and 15m.

I have so far only completed building the 20m LPF, and so this is installed in position 4, leaving positions 5 (30m), 3 (17m) and 2 (15m). The only other thing to do is make sure that the correct 'band', that is, the relay position number, is set in the software so that  the corresponding filter is selected to match the operating frequency. I have already modified my two transmission settings for 40m and 10m to match the new filter arrangement.

I have also recently been trying to program some old Philips PRP70 series radios, but so far without success, despite having a genuine programming lead. I suspect theres a corrupt file in the software, as it throws up a run time error that seems to relate to file handling in MS-DOS. I have three of these radios and only really need to get one working, as that will go on 4m.

More bits ordered from the Far East are beginning to trickle in. Several cheap multimeters, just to give me some extra metering capabilities, but one of the little analogue meters ive had to have refunded, as it is totally dead! I suspect i'll be able to fix it so long as its not the coil in the movement itself.

Ive also received the 24v 3A SMPSU block, which, as feared, is slightly wider than the 1Ah clansman battery case i'd hoped to fit it into! I need to test it anyway first, but I think I will have to look out for a 4Ah metal cased battery to decell and turn into a mains supply instead. I could perhaps switch the casing on the LiPo pack.

Tuesday, 1 November 2016

Ultimate 3S WSPR Beacon Success

After some further testing, I moved the U3S into the shack today ready to go on air. Some advice from Hans Summers regarding the GPS module allowed me to get that working, and after a number of false starts due to settings, it went on air on 28MHz around lunch time.

Not a single spot!

10m conditions clearly not up to much today! Powered from a 12v 7Ah SLAB, via a modified 3v/5v regulator board (el cheapo, intended for Arduino and R-Pi prototypes), the U3S was working away quite happily, so I changed the frequency, swapped the LPF, retuned the DX-70, which was acting as monitor receiver, and moved to 40m...

And was spotted a dozen times on the first transmission!

Ive been running on 40m since then, at 10min intervals, heres the spots for the last 6h -

Not bad for a mere 200mW! Rather than try and explain what the U3S does when its running, ive done a little bit of a video of it. This shows it from just before transmission, when during the gap it displays the GPS data, to just after the start of a WSPR transmission


Immediately after transmission, the beacon calibrates itself using the GPS 1PPS signal, before putting the synthesiser into 'Park', that is, running but on a frequency safely away from the operating band, to keep it warm and so avoid drift,

I will try 10m again tomorrow.

Clansman PRC-349 on 6m?

The PRC-349 is generally shunned by the amateur community, being as it is the bog-brush haired back-stairs sprog of the Clansman range. Its quarter of a watt output power is mediocre at best, and its 150Hz tone squelch system makes it awkward to interwork with non-Clansman radios. But perhaps its biggest drawback is that it doesnt cover any amateur bands.

Shame really,

But should this be the end? Why cant it be converted? This is something ive been looking into.

There are a number of problems that would need to be overcome in order to move the 349 to somewhere it might be useful -

- Its coverage 37 to 46.975MHz
- Its tone squelch system
- Its 25kHz steps

Lets look at each of these in turn,

Coverage - ok, so its a good way from anywhere, but, the move to 6m (50MHz) from 46MHz isnt too far, and the front end might just adjust, if not, it shouldnt be too hard to retune.

Tone Squelch - The squelch system needs to see a 150Hz tone at >3mV at the discriminator output. Hmmm, shouldnt be too hard to inject a suitable tone here

25kHz steps - ok, so this is harder. But - we would also need to pretty much replace the Tx and Rx VCOs and the synthesiser anyway to convert the set, so the new control system would just be built for 10kHz steps as required.

Heres my thoughts - Replace the synthesiser and the VCOs with an Arduino Nano, and a DDS module. Most DDS modules have multiple outputs so one for Rx and one for Tx. The original switches could be reused, or other suitable types fitted to get easily selectable steps. The Arduino takes care of all that. The Tx mic audio would need to be modulated onto the Tx side of the DDS, I believe this is not too hard to do. Some waveform shaping I think might be needed though. The Arduino can generate the tone to defeat the squelch.

Perhaps a trial on the bench might be in order...

Monday, 31 October 2016

Ultimate 3S - It Lives!

In between boxing up parcels, and scaring kids with my S10 respirator (in my defense it is Halloween!) ive had chance to power up and configure, partially, my Ultimate 3S beacon -

I had a few difficulties at first, due to a crocodile with a wide mouth! It turned out that the crocodile clip I was trying to use had been over stretched and its teeth didnt quite come together, so my -ve lead kept falling out!

It took some time for me to become familiar with the menus and the setting process. I managed to eventually get my callsign and locator set, and a WSPR mode transmission set up. I then had to go Trick or Treating with Tom,

These are the pumpkins I carved yesterday, suffering intense cramp in my hand as a result!

Back in the workshop, timing was set reasonably successfully using my watch. The power output was a doddle to set though, although my QRP power meter and dummy load isnt calibrated! I used my Alinco 2m handheld to calibrate it roughly, by measuring the handheld output on the Marconi 2955, and then seeing what that power read on the QRP meter. With the one BS170 MOSFET, it seems I am getting a comfortable 1/4W, or there abouts. Frequency was more awkward. For a start, I wasnt at all sure what to set! Luckily I discovered the table of sub-bands in the manual, and was able to set up for the center of the band. Then I managed to eventually find my signal on my main radio, which is acting as test receiver.

I eventually worked out, after a few false starts getting great decodes of my own spurii, that I was about 4kHz off frequency. Without the GPS module in use, I had to do a manual calibration. The instructions for this turned out to be in the assembly manual, not the operating manual!

My frequency is now roughly in the middle of the operating window. My own decodes are a bit intermittent at present which im putting down to having set the synthesiser to turn off between transmissions, which I think is causing a bit of a chirp! The 'park' control in the firmware is for telling the synth what to do between active transmissions, so I will set that back to an 'on' state.

The above screenshot shows my WSPR signal, and the recent decodes.

Before I can put the beacon to air though, I need to build a 5V regulator board for it, to allow me to run it from a 12V supply. This is a task for tomorrow.

Box Disappointment

Slightly put out today I'm afraid. Ive finally come today to testing the CRS L/R box I got as part of my order around a month ago from PTS. Unfortunately, theres a problem. The headset audio 'motorboats' and the control functions dont operate. Ive tested it with alternative cables to ensure it wasnt a wiring issue; on two different radios (different types, a 320 and a 350); and with different audio kit.

This is a real disappointment, but not a disaster. Ive emailed Graham at PTS about it, mainly to see if he can direct me to the necessary EMER in order to fault find and hopefully repair the unit. Ive also opened it up to check for any obvious issues, which gave me a bit of a shock as I wasnt expecting it to be anything like as complex as it is!

It is indeed beautifully made, but daunting! I really dont fancy taking it on without a schematic!

On the positive side though today, ive sold on quite a few of my excess PRC-349 batteries, and also the remaining excess PRC-349s! This has effectively covered my original costs, and raised me sufficient funds to progress a few other radio projects.

My list of projects that need completing though is still looooong! Ive made a start of restoring the Clansman hand generator, but thats just a bit of a lick of paint. My next two priority tasks are to test the Ultimate 3S beacon, and to complete the refurb of the PF8, now that I have the capacitors.

The various small modules are beginning to trickle in from the Far East now. The Arduino Mega has arrived, so Im in a position now to be able to start working out the control system for the PRC-320 Remote project. Im short of just the display module for the camera dew heater, with any luck that will come in the next week or so, so that should be finished and ready for the winters night photography.

Friday, 28 October 2016

WhiSPeRs in the night

Ive decided, as of 23:10 UTC, to run my 7MHz WSPR station at 15% Tx and 27dBm (thats 500mW) overnight, and see just where I hear and where hears me,

This is around about the sort of power i'll be setting the U3S up to run when its complete.

Thursday, 27 October 2016

Rishworth UKBB RF Probe made permanent

Despite its simplicity, and that it was intended as a very quick to build, 'no-solder' project, I was so impressed by the neat little RF Probe kit supplied by Rex W1REX or QRPme for the G-QRP club Rishworth Conventions 'UKs Biggest Buildathon, that I decided to actually solder it!

I didnt want to tag solder to the IC socket, as I felt this would look untidy. So I took the drastic decision to remove the socket. Rather than struggle to desolder so many pins, I did this (may Rex forgive me!) destructively - by cutting away the body of the socket and then using a heat gun to melt the solder and allow me to knock out the pins.

The result is now a very neat permanent rebuild, which will eventually get a nice little round housing, a sharp probe, and some nice leads with 4mm plugs on them

I retained the original vertically mounted zero-ohm links, rather than replace these with wire links, so I can still use it as is, before it gets boxed up.

Release the Hydra!

It should be the Kraken, of course, but ive never found mythical sea monsters to be particularly useful in bulk charging batteries!

The Hydra in this case is a simple multi-headed trickle charging solution! Ive found that many deeply discharged batteries will recover, but the Accucel-8 cannot detect them! So, by sticking them on a 15v supply with a suitable series resistor, in this case 120 ohm, I can bring them back up to around 11-13v terminal voltage, and the charger will then detect them and go into the recovery cycle.

The 'Hydra' trickle charger!

With quite a lot to get through, I set up the 'Hydra' to allow me to bring up half a dozen or so batteries in one go.

Ive now run around a dozen through a pair of full Discharge/Charge cycles, and they all seem to have come up to sensible capacity. Around another 50 have passed basic on-load voltmeter testing and should recover when given the cycle charging. About a dozen have failed completely to recover at all

I can now at least dispose of all the known failures, and concentrate on those that show promise. As such, I am also now in a position to separate the 600mAh packs from the bulk of the 550mAh packs! I want to retain around ten good packs for my own use. All the rest can be sold on. Two lots of untested packs have been sold, thats 20 batteries. Im slowly clearing the space in the workshop!

Very kindly, one of the BVWS forum members, Tony, has sent me some 5p6 ceramic capacitors of the type I need to complete the PF8 refurbishment.

I shall get on to that shortly. It now requires some serious dismantling to change these capacitors, due to them being very close to the chassis edge.

The Ultimate 3S is coming along, slowly. Ive not yet heard from Hans regarding the missing inductor, but theres no rush. Ive completed the 10m LPF, this time without getting my wires crossed!

28MHz LPF, L1 (10t) fitted
28MHz LPF L1 and L3 installed and glued down
28MHz LPF complete
Ive also made up the RF coax connection header. This is using my TNC pigtail at present but will do for testing. I dont wish to power the unit for testing until I can have the output fed to a dummy load

RF coax header connection
Ive been hearing a lot recently about 'Parrot Repeaters', otherwise known as a Simplex Repeater, a type of Voice Store And Forward system. These are used on 70MHz where there is insufficient bandwidth for duplex repeaters, and generally seem to be much simpler to build. Im wondering if there is any such machine im my area, and if not, what the requirements would be for me to instigate one...

Tuesday, 25 October 2016

Chance of Aurora and no visibility

Past few nights have had lovely clear, starry skies, tonight theres a class G3 geomagnetic storm

and its bloody overcast again!

There seems to be a correlation between likelyhood of visible Aurora, and how bloody cloudy it is in the UK!

Ive done a slight bit of work on the Ultimate 3S today, such as making up the power cable and the cable to link the GPS module. Ive also ordered a BNC panel socket with coax pigtail in order to make the RF connection. The pads to connect are too small to safely solder coax to, even the very thin stuff I have, so ive added another pair of header pins. I can either solder direct to them, or put a plug on the coax. It will probably be a couple of weeks before the cable arrives, but in the meantime I can test using the only other coax pigtail I have that will fit, which is currently attached to the prototype Wispy project that I couldnt get to work for me. The reason im not just using this on the U3S is that the coax connector on it is a TNC!

I also need to find a suitable case for it! The U3S itself needs a metal box, ideally one that I can modify to accommodate the battery housing from a PRC-349, but then a plastic box will need to be attached onto the metal one to house the GPS unit. The plan being to make the whole thing completely portable - just attach antenna and switch on!

Ive just returned to 40m WSPR - as expected, the geomagnetic storm has pretty much wiped out HF propagation, but, there are a few spots to be had!